Zeolite Y catalyst

The deactivation of a lanthanum exchanged zeolite Y catalyst for isopropyl benzene (cumene) cracking was studied using a thermobalance. The kinetics of the main reaction and the coking reaction were determined. The effects of catalyst coke content and poisoning by nitrogen compounds, quinoline, pyridine, and aniline, were evaluated. The Froment-Bischoff approach to modeling catalyst deactivation was used. 

A rather interesting application of zeolite-based alkene oxidation catalysis has been demonstrated by Japanese workers (46, 47). In particular, a Pd2 +, Cu2 +Y zeolite was shown to be an active and stable heterogeneous oxidation catalyst which is analogous to the well-known homogeneous Wacker catalyst system containing PdCl2 and CuCl2 (48). Under Wacker conditions (i.e., alkene/02/H20) the zeolite Y catalyst was shown to convert ethylene to acetaldehyde and propylene to acetone with selectivities in excess of 90% with C02 as the major by-product. 

The NiY zeolite was also shown to be active for the cyclotrimerization of propyne with 1,2,4-trimethylbenzene being the main product. The activities of the above-mentioned transition metal ions for acetylene trimerization are not so surprising since simple salts and complexes of these metals have been known for some time to catalyze this reaction (161, 162). However, the tetramer, cyclooctatetraene, is the principal product in homogeneous catalysis, particularly when simple salts such as nickel formate and acetate are used as catalysts (161). The predominance of the trimer product, benzene, for the zeolite Y catalysts might be indicative of a stereoselective effect on product distribution, possibly due to the spatial restrictions imposed on the reaction transition-state complex inside the zeolite cages. 

Ercan et al. studied the alkylation of ethylbenzene, EB, with light olefins (ethylene and propylene) over a commercial zeolite Y catalyst in a fixed-bed reactor with recycle [C. Ercan, F. M. Dautzenberg, C. Y. Yeh, and H. E. Earner, Ind. Eng. Chem. Res., 37 (1998) 1724]. The solid-catalyzed liquid-phase reaction was carried out in excess ethylbenzene at 25 bar and 190°C. Assume... 

J. M. Thomas, C. Williams and T. Rayment, Monitoring cation-site occupancy of nickel-exchanged zeolite Y catalysts by high-temperature in situ X-ray powder diffractometry, J. Chem. Soc. Faraday Trans. 2, 1988, 84, 2915. 

CO2 and H2 chemisorption studies were performed on supporting materials and iron supported on HY KY zeolite catalysts to determine the relative basicity. The results were listed in Table 2. No chemisorption of CO2 was observed on the HY and KY zeolite. However, the chemisorbed amount of CO2 increased with increasing the iron content on the supports. By the way, iron supported on potassium ions in zeolite-Y catalyst showed a much higher chemisorption capacity of CO2. From these results, it is concluded that CO2 appears to chemisorb on the free iron surface and on the iron surface on the potassium present in the zeolite matrix. The addition of potassium into Fe/HY and Fe/KY catalysts slightly increased the chemisorption amount of CO2 due to the electron donating ability of potassium to neighboring surface iron atoms. On the other hand, the chemisorbed amount of H2 did not show considerable difference in all samples. 

The most detailed study in the diethylbenzene system is that of Bolton et al. (1S5), where partially cerium-exchanged, partially decation-ated zeolite Y catalysts were employed. All reactions were run at 170° in the liquid phase, essentially under alkylation conditions. Their findings are summarized in the reversible reaction scheme below. Starting with any one of the three diethylbenzene isomers, the same equilibrium product distribution was obtained about 21 mole % ethylbenzene. 

Cavaeanti, F., Stakheev, A., and Sacther, W., Direct synthesis of methanol, dimethyl ether, and paraffins from syngas over Pd/Zeolite Y catalysts, J. Catal., 134 226-241 (1992). 

Figure 6 Comparison of the distribution of products from decomposition of polypropylene at 673 K with the addition of zeolite Y catalysts ...

Carbon monoxide (C=0) and hydrogen (H2) produce methanol (CH3OH) on a ruthenium-exchanged zeolite-Y catalyst within a mbular reactor. Propose a mechanism and develop a kinetic rate law which accounts for the fact that a heterogeneous surface-catalyzed reaction occurs within the internal pores of the zeolite catalyst. Hint There are no hydrogen-hydrogen bonds in methanol. 

Keane et al. have found that the gas phase hydrogenation of butan-2-one to butan-2-ol can be accomplished with an ee of 31% at 70°C over a 2.2% Ni-Zeolite Y catalyst modified with 0.008 mol/L solution of L-tartaric acid. The optimum particle size of the catalyst was found to be 3 nm (this size seems to be important in catalysis ). Modification of catalysts with solutions of L-Val or L-Glu had a negative results on enantioselectivity. 

Boehmer, U., Morgenschweis, K., Reschetilowski, W. (1995) Liquid phase as5mimetric hydrogenation on Pt-containing zeolite Y catalysts, Catal. Today lA, 195-199. 

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